<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        box-sizing: border-box;
        margin: 0;
        padding: 0;
      }
      body {
        width: 100vw;
        height: 100vh;
        background: linear-gradient(
          135deg,
          hsl(170deg, 80%, 70%),
          hsl(190deg, 80%, 70%),
          hsl(250deg, 80%, 70%),
          hsl(320deg, 80%, 70%)
        );
        background-size: 200% 200%;
        animation: gradient-move 15s ease alternate infinite;
      }

      @keyframes gradient-move {
        0% {
          background-position: 0% 0%;
        }
        100% {
          background-position: 100% 100%;
        }
      }
    </style>
  </head>
  <body></body>
</html>
